1. Field of the Invention
The present invention relates to a rotation angle detecting device for detecting a relative rotation angle between two members without contacting the members.
2. Description of the Related Art
JP-A-2003-75108 discloses a rotation angle detecting device that detects a relative rotation angle of one member to another member by means of a permanent magnet and a pair of magnetic sensors. The pair of magnetic sensors is fixed to the one member to be spaced apart from the other at 90 degrees in angle and disposed to confront the permanent magnet that is fixed to the other. Therefore, magnetic sensors are disposed near the permanent magnet, which forms an open magnetic field. That is, the lines of magnetic flux in the open magnetic field radially but unevenly spread from the peripheral edge of the permanent magnet. Accordingly, the output signal of the magnetic sensor may vary if the position of the magnetic sensor is shifted, resulting in a detection error of the rotation angle.